Writing this knowing that this is a work-in-progress still.
There are two things that immediately jump out to me, though they may be more personal issues and not something that's actually wrong with the piece.
The first is her pose. It feels like she is arching her back, almost like she's leaning back from the waist up. This may have been a style choice, and that may be the pose you're going for, but if not, you may want to take a closer look at her upper back. Like I said, it feels like she is sort of leaning back for some reason.
The other thing that jumped out at me is the proportions of her upper body. Specifically, it feels too short in relation to the length of her legs. At first I thought it was her legs that were too long, but if you were to shorten them in proportion to her torso, she would seem far too short, so I realized the problem must be the upper body. It just feels like it's too short. I'm not sure if it actually is, or if it relates to the POV or pose, though.
Overall, though, I can't wait to see where this goes once more polished. The background is set nicely, her pose (other than the aforementioned lean) is very nice, and I love the design for her armor. Very well done take on an iconic character.